Method for the separation of gas mixtures



Aug. 23, 1955 R. BECKER METHOD FOR THE SEPARATION OF GAS MIXTURES FiledOct. 25 1951 Sluicing Gas H j 6 Residual Gas f CHE; 6a

co: gamma 2 J! l A Sluicing Gas cotuzoumw EPQ United States PatentMETHOD FOR THE SEPARATIGN OF GAS MIXTURES Rudolf Becker, Munich-Solln,Germany Application October 25, 1951, Serial No. 253,020

Claims priority, application Germany November 30, 1950 3 Claims. (Cl.62175.5)

The invention relates to the purification of gases by deep cooling thesame in regenerators.

The use of pairs of filler loaded deep cooled regenerators through whichgas mixtures are alternatingly conducted in opposite directions orconducted in alternatingly opposite directions are generally known inthe art. Uniformity of operation and a satisfactory removal of theimpurities deposited from the gas mixture is their importantrequirement.

The operation of these regenerator pairs is based on the followingprinciples.

The regenerators are charged with filler masses and the latter areheated during the so-called hot period by the initial gas mixture, thesemasses being maintained at a lower temperature as the gas, the latterbeing during the hot period conducted over the filler masses and cooled.During the cold period the filler masses are cooled by the purifiedresidual gas and the thus separated impurities may be evaporated.Therefore, the regenerators are heated by the initial gas in the hotperiod and cooled during the cold period by the purified gas.

While maintaining during a normal operation an equal heat capacity ofthe inflowing initial and outflowing purified gas, an excess is requiredof the purified gas over the initial gas to completely evaporate andsublimate the impurities which have been separated from the gases in thefiller masses.

The requirement can be met without diificulty, if the pressure of theinitial gas is substantially higher than that of the purified gas.

Difficulties, however, arise if the pressure of the initial gas is onlyslightly higher than that of the purified gas.

It is a main object of this invention to enable the maintenance ofsatisfactory work of the regenerators, at a substantially equal pressureof the impure and of the purified gas as well as the use of a lowpressure for the gas separation, whereby highly economical operatingconditions result.

It is a further important object of the invention to fully preserve theadvantages of the regenerator work in spite of the maintenance of only asmall difierence between the pressure of the impure gas and the purifiedgas.

In compliance with these objects, the invention comprises in a methodfor the purification of gases the steps of deep cooling in apurification set composed of at least three regenerators charged with agas purification material, flowing the impure gas in one directionthrough one regenerator to remove the impurities by condensationsimultaneously flowing deep-cooled pure gases in the opposite directionto the flow direction of said impure gas through a second regenerator,repeatedly changingover said two gas flows from one to the otherregenerator within equal time periods, flowing a sluicing gas at a rate,which is essentially smaller than the flow rate of the gas passedthrough each of said two other regenerators, from the cold end to thewarm end of a third regenerator, changingover the gas flow from saidthird regenerator to one of said first named two regenerators, operatingthe latter in "ice ' 2 the manner of said previous third regenerator andcontinuously repeating said change-over step through the entire set ofsaid regenerator.

The term purified gas is here used to define the cold gas, which remainsfrom the impure gas after separation of a major part of the impuritiesby deep-cooling; it has a slightly lower pressure than the impure gas.The additional gas used for sluicing purposes is denoted as the sluicinggas; this sluicing gas is deep-cooled, free of impurities and has asmaller pressure than the impure gas. The regenerators used in theperformance of my invention should preferably have a high heat capacity.

From experience gained with the invention, it was found that a volume ofsluicing gas amounting to at least 1.4 times that of the impure gas isrequired to secure a complete removal of the impurities by evaporationand/ or sublimation while maintaining a temperature difference of 2 C.at the cold end of the regenerators.

If the temperature of the sluicing and of the purified gas issubstantially the same, a proportion of the volumina of sluicing gas andimpure gas of 1:15 is suflicient to remove the impurities and tomaintain satisfactory temperature and evaporating conditions.

The invention enables the passage of the impure and of the purified gasthrough the regenerators at an equal pressure. Pressure losses duringthe reversal of the gas flows may be practically avoided or entirelyeliminated, if the pressure in the two regenerators coupled for thepassage of the impure and the purified gas flows is maintained at aboutatmospheric pressure.

The invention may also be carried out at a subatmospheric pressure,whereby the gas flow is effected by suction, the latter being preferablyapplied at the end of the gas flow through regenerators. This mode ofoperation is particularly recommended if the treated crude gas isentirely pressure-free or contains corrosive components, which attackthe compressors.

During the short reversal periods, for instance, of about 2 to 30minutes according to the invention, the impurities cannot be completelyevaporated by the purified gas flow; this is only secured by thesluicing gas passed through a third further regenerator during the timeof repeated reversal flows of the impure and the purified gas throughthe two regenerators. The sluicing gas is therefore only entered intothe latter after the completion of a predetermined series of flowreversals of the impure and purified gases.

It is recommended to apply the cold sluicing gas prior to the purifiedgas period, since due to the small quantity of the same the evaporationand sublimation of the impurities takes place at a higher temperaturethan that of the preceding impure gas period.

A gas may be used for sluicing purposes, of which the temperature ishigher than that of the residual gas; the

' quantity of the sluicing gas may be reduced thereby; in

this case, the siuicing gas is passed through the regenerators as a sortof a heat wave shortly before the passage of the residual gas.

The invention is schematically illustrated in the accompanying drawing,showing a vertical section view of a set of three regenerators.

The numerals 1, 2 denote two regenerators, which in the shown phase ofthe operation, are to be reversed within short periods from coke gas toa substantially equal quantity of purified gas and vice versa, the gasesbeing maintained at a substantially equal pressure. Numeral 3 denotesthe third regenerator to be passed by the sluicing gas for a time whichequals that of several, for instance, at least three reversal flows ofthe two other regenerators 1, 2.

Numerals 5, 7 denote the conduits for the flow of the coke oven gas,numerals 4, 6 for the flow of residual gas and numerals 8, 9 the, flowof the sluicing gas; the 1 i 31, 32, 33, 36 the forciblycontrolled'change-over valves.

-the change overvalves l6,-26,- 36-are located at the {cold end 'of theregefie'rato'is; the residu'al" changefover heavy hydrocarbons andthe'like."

conduit'4 into thesecond' fegien er'atbr 2, 'the'gas entering sentiallythe sam'etemperature"asfthepurified gas, are H conducted withoutpressure from conduitfj through valve 37 into the third regenerator 3and therefrom through --'valve 33 into co'nduit' 9 and dischargedtherefrom;

to' -6'minutes, the impure coke gas-is switched from regenerator [toregenerator' 2 -a'nd the purified'ga'sfrom :13 third,re'generator,"'changingaaverthe gas iflowvfrom said regenerator 2 to'l,the sluicing 'gas flows' durin'g'this' time thr'o'ugh reg'enerator3ifwithou't adirectional change.

Hereupon the impure coke gas is switched to'regenefator 1"andthejpurifiedfgas' to regenerat'or"2, whereas unchanged." The sluicing' gas-is"direcfedfrom'regenera- 'tor 3 to the regenerator 1 only after afurther switching of the iinpu're and the pur ified gas; the coke 'gasis'now directed into rge L generator 3.

sublimation takes place 'at 'aslightly higher "medium temspend to theratio of about 1 :"19: sp --pe'rature than the temperature of the impure'gasf' The 60 to the'chang'e-over to-coke 'gas'. a

the following table, the flow reversal in the regenerators 1, 2 takingplace after always'threeminutes; Regenor ea ri t w rduif f t it j Purifiisa new the word up the up flow direction of the gases; the filettersa-g denote the individual switching stages; the letters a. s-:-f.indicate-that-theprocess-is further -eontinued in the described manner.

numerals 15, 17, 25, 27, 35 37 denote automatic check valves and thenumerals 11, 12, 13, 16, 21;"22', '23, 26,

K operation:

As previouslymentioned, the switching of the sluicing gas into theregenerator, which has been previously passed by the impure coke gastakes place in accordance with this table after always three flowreversals of the impure The automatic check valves 15, 17, 25, 27, 35,37-,'and

yalvefi are located lat the; upper end thereof.

through the regenerator andthecooliiig thereoffl 'l his f switchingscheme ma however? beninodifiedi and the 'sluici'ng'gasmaybe"switchedovenafter 5"or7 reversals. 'Sine certainIchangesdrfcarrying out'thabove process 5,001) cub i cj meters of coke fliavinga n'nnai' t'e'mperature are conducted throiighiconduit 5 andregenerator 1 by mean s ofthe fcharige-over' valve ll'lan'd'clie'ck'valve 1 "15, the 'regeneratb'rs being charged with acustoiniary25"cou'ld bmade without'departing-from the scope thereof,

:granular ltiller"massflthegas is cooled fo' Z O' 'C. andtherebyliberatedfrom impurities, such as watnvap'or,

it is intended that all matter contained in the above description'ofshown in the accornpanyi'ngdrawing shallibe interpreted as illustrativeand not in a lintitingf's'ense. Having thns"described"the inveiitionWhattl claim as A slightly smaller quantity of about 4800 cubic meters Ipurified gas resulting from the purification of the coke 30 new anddesire to be secured"' by *Letters Patent; is as gas bydeepcoolingandhaving'afternperatlire of "''82 'C.

f 1lO H 7 in. V I, v- 5,

lrlntfi'e inethod forthe purification bfgases-thb steps 'of'deep coolingin a purification set composed of at least 7 three regeneratorschargcdwvithe a ga's --"purifi :atiou ma- 5" terial the step'offidifiingthe irfipur'gas in one direction ""th'ro'ugh on'e regenera'tol'to remove E'the-inipuritiest' by condensation; siinultanedusly Fflowihg3 deep coled' apure ""gas 'in the oppositei'direction :to'the flowdirection ofsaid irnpure' 'gas through a'"second*regenerator;*repeatedly is passed at ane'qual pressure asthecrude coke'ga's' from through reversing valve26 'andileavingat'aboutnormal temperature through'valve zz'ana conduit"26. f250 'cubicmeters of sluic'ing' g'a'slwhich' may have es- "reg'eneratofwithifiequal time period'sg flowing a slfiicing "gas af'afate'; which isessentiall-y' smaller-*than the flow rate of the gas passed through eachof said two other regenera'tors, from'thecold end =to the warm endibf a'The switching'seheme of the 're' gene'rat ors is performed as fQllOWs.'7 i 4 i lAft er' a predetermined periodof 'a' few, for instance 2 thirdregenerator to one of said first named two'lreg'entera'torsjofi'eihtingthe latter-in it'he 'manne'r 10f. said previous third regenerator'hndcontinuou'sl-y" repeatingasaid change-over step through the entireset aifsa-id e'genthe new of the sluficingfgas through regenerator' 3remains 59" 'eiators":

"2' i 2. Ida method"accordingtoclaini 1" the stepofa performing thechange-overt from the third regenerator to the cooperating'paii' 6f? theother twoeregerferators after a directional-"reversal of the gas flowin: the-saidr'gen- In conformity with a variation of the describedoperational sequence, the coke gas flow is first, followed by a sluicinggas flow. }In' this case, the-cooperatiofi and amount of the gas flowsin the third regenerator and in the-icooperatingipair-'of said twqregenerafors to 'corre- References Cited in the file of this patent"lJNlT-ED STAT ES PATENTS,

1,402,349 B urrell gal. Jan. 3, 1922 ,5 3,716 Yor et all regenerator iscooled in this case by the purified gas'prior An example of theswitching scheme'i'sapparent from by the sluicing gas. v g u j Each'horizontal row of the table indicates a switehing n a i tt s WW .f mdids s lt s r d astfl erator 3 is passed during thevariou's r'eversal'periods or cooling period; ,the word sjluiee the sluicing the word.vfdownf den 'tes t hedow'nflo'w 40 changing-over s'aid'two 'gasflowsfrom -one to the 'other 3': In a method according to= elaini'l;controlling" the 7

1. IN THE METHOD FOR THE PURIFICATION OF GASES THE STEPS OF DEEP COOLINGIN A PURIFICATION SET COMPOSED OF AT LEAST THREE REGENERATORS CHARGEDWITH A GAS PURIFICATION MATERIAL THE STEP OF FLOWING THE IMPURE GAS INONE DIRECTION THROUGH ONE REGENERATOR TO REMOVE THE IMPURITIES BYCONDENSATION, SIMULTANEOUSLY FLOWING DEEP-COOLED PURE GAS IN THEOPPOSITE DIRECTION TO THE FLOW DIRECTION OF SAID IMPURE GAS THROUGH ASECOND REGENERATOR, REPEATEDLY CHANGING-OVER SAID TWO GAS FLOWS FROM ONETO THE OTHER REGERERATOR WITHIN EQUAL TIME PERIODS, FLOWING A SLUICINGGAS AT A RATE, WHICH IS ESSENTIALLY SMALLER THAN THE FLOW RATE OF THEGAS PASSED THROUGH EACH OF SAID TWO OTHER REGENERATORS, FROM THE COLDEND TO THE WARM END OF A THIRD REGENERATOR, CHANGING-OVER THE GAS FLOWFROM SAID THIRD REGENERATOR TO ONE OF SAID FIRST NAMED TWO REGENERATORS,OPERATING THE LATTER IN THE MANNER OF SAID PREVIOUS THIRD REGENERATORAND CONTINUOUSLY REPEATING SAID CHANGE-OVER STEP THROUGH THE ENTIRE SETOF SAID REGENERATORS.